18 REPORT OF SCHIMMEL & Co. OCTOBER 1915. 
obtained, as discussed on former occasions (Report April 1908, 50), if cineol is separated 
as a solid resorcinol compound and the latter decomposed; at all events as far as 
reliability is concerned, this method of determination is not in any way inferior to 
any method recommended in other quarters, and it has the special advantage of the 
addition product of cineol with resorcinol being the most easily handled of all these 
compounds. 
Of late the resorcinol method has once again been checked by H. G. A. Harding’). 
Even with the modified method he obtained useful results only in cases where the 
cineol content did not exceed 50 p.c. Otherwise even here the results were found to 
be too high., He suggests that in cases of too high a percentage of cineol, fraction 
170 to 190° should be diluted with turpentine oil to such an extent that the cineol content 
is reduced to about 40 p.c. The mixture is then to be shaken with hot resorcinol lye, 
which he uses in 55p.c. strength. To obviate possible mistakes, he does not use 
ordinary turpentine oil for the dilution, but the fraction boiling between 156 and 160°. 
As will be found from the figures published by us at the time, we arrived at 
correct results by the modified method, even with oils containing more than 50 p.c. 
of cineol. 
A contribution to the determination of eucalyptol is furnished by J. L. Turner and 
R. C. Holmes’). They are of opinion that none of the methods proposed so far yield 
satisfactory results. The determination of the cineol percentage by means of phosphoric 
acid meets with difficulties, inasmuch as the addition product is of sticky consistency 
and decomposes very rapidly. The same may be said as regards the hydrobromic 
acid method, and the permanganate of potash method recommended by Dodge also 
proves ineffective (compare Report April 1918, 62 and Report April 19t, 71). The 
authors attack the resorcinol method more especially, because it has been suggested 
for inclusion into the new American Pharmacopoeia. They pretend that, even with the 
modified method, the results obtained are invariably too high, a statement about which 
there may be two opinions, seeing that we ourselves arrived at the opposite result, 
for which we produced experimental proof at the time. Be this as it may, Turner 
and Holmes are no doubt of a different opinion and have therefore cast about for a 
new test. In arsenic acid they believe to have found a compound which is far better 
suited to the quantitative analysis of cineol than all the other compounds suggested 
so far. The use of arsenic acid for separating cineol from eucalyptus oil and kindred 
articles is far from being novel, having been patented to the firm of Merck in Darmstadt 
in 1901 for the production of eucalyptol (D. R. P. 132606). Its use for quantitative 
determination of cineol was therefore indicated, and the only reason why, at the time, 
we had refrained from making use of it was that in arsenic acid we have to deal with 
a powerful poison, and because, moreover, we consider the addition product with 
resorcinol even more suitable. Of this fact we are fully persuaded to this day. There 
can be no doubt about it that for the purpose in question arsenic acid is far superior 
to phosphoric acid, but it is equally certain that at the very least equally satistactory 
results are obtained by means of resorcinol. 
For the test with arsenic acid, Turner and Holmes give the following directions: 
“Deliver from a pipette 10 cc. of the oil into a glass dish of 50 cc. capacity, 
which is embedded in finely cracked ice. Add 10 cc. of concentrated arsenic acid 
(containing about 85 p.c. arsenic acid) and stir until precipitation is complete. When 
1) Analyst 39 (1914), 475; Journ. Soc. Chem. Industry 88 (1914), 1171. — 7%) Perfum. Record 6 (1915), 20. 
After a paper read at the November meeting of the New York section of the American Pharmaceutical Society. 
